[HN Gopher] The company building a rotating detonation engine is...
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The company building a rotating detonation engine is pushing the
tech forward
Author : CharlesW
Score : 52 points
Date : 2024-03-28 14:32 UTC (8 hours ago)
(HTM) web link (arstechnica.com)
(TXT) w3m dump (arstechnica.com)
| jtriangle wrote:
| All of these hypersonics companies are targeting mach 5 for a
| reason, which is that the material science hasnt caught up yet.
| The bet seems to be that they'll either be ready once it is, or
| they'll be the ones to develop it and start raking in a mountain
| of military industrial complex cheese.
|
| Not a bad goal, but the thin vernier of 'passenger flight' leaves
| a bad taste in my mouth. This tech is for munitions delivery
| first, the meatbag ferry is squarely a side hustle, and I wish
| they'd be honest about it.
| Havoc wrote:
| A fair bit of vehicles go well north of 5 already so propulsion
| aside I don't think the hurdles are massive. And propulsion
| seems to be what everyone is focused on
| nordsieck wrote:
| > All of these hypersonics companies are targeting mach 5 for a
| reason, which is that the material science hasnt caught up yet.
|
| My understanding is that mach ~5 is when ramjets hit their
| limit and you have to transition to scramjets if you want to go
| faster.
| MilStdJunkie wrote:
| That's also right around where aerodynamic forces are
| _juuuuuuust_ starting to transition to disassociation and
| ionization in high flow areas, as the electrons are ripped
| from molecules in the air. Probably not a coincidence,
| because a very _ooooof_ zone will be the ramjet intake, since
| ramjets need to slow the air to subsonic for combustion. Lots
| of these high mach ramjets have _amazing_ cooling devices on
| the intake.
|
| These RDEs are especially neat because the exhaust mass is
| moving supersonically but they're very choosy about the mix
| in the combustion chamber, so and air-breathing RDE will be
| doing some sort of voodoo in that department. If they riddle
| it out they might get a single engine that functions
| throughout the airspeed regime.
| IntrepidWorm wrote:
| It does feel disingenuous, but its also nothing new. Military
| research has always been the one of the primary driving forces
| behind critical technology.
|
| Commercial tech is vulnerable to all sorts of disruptions,
| regulations, and setbacks. If you make something that will make
| killing a whole bunch of people easier, rest assured theres a
| global market for it.
| alex_young wrote:
| Are they targeting Mach 5? The second paragraph of TFA says
| "The company's long-term ambition is to develop a commercial
| aircraft that can travel at Mach 9".
|
| They mention that goal a couple of places, and state that
| hypersonic is defined as Mach 5 or more.
| AnarchismIsCool wrote:
| I'm in the industry... It's a constant psychological game. The
| type of highly educated people necessary to pull off these
| ventures are less interested in being part of the MIC than they
| used to be. Nationalism in that crowd is thankfully much less
| aggressive than it was during the cold war. As such, founders
| have resorted to lying about their goals so they can expand
| their applicant pool for developing the tech, then "pivot" and
| get acquired by Raytheon et al.
|
| I also think to some extent there are employees who know but
| semi-appreciate the cover. In a prior life, I worked on some
| stuff that's, unfortunately, currently being used to murder
| people in the middle east. That just doesn't make good small
| talk at parties.
| eschneider wrote:
| Rest assured, founders who'll lie to their applicant pool
| about that will lie to their applicant pool about anything
| inconvenient.
| buildsjets wrote:
| It may have hurt me financially and limited my career
| opportunities, but this is one reason why I refuse to work on
| any technology that requires me to have a security clearance.
| It's a decision I made way back at the end of the last
| century and it has served me well throughout ~25 years of
| aircraft development while the world has been at continuous
| war, and mostly kept me out of military programs.
|
| Also, I took one look at the SF86 and said F that, no
| government deserves that information, so I didn't get screwed
| in the Department of State OPM hack like all the other
| suckers.
| JumpCrisscross wrote:
| > _may have hurt me financially and limited my career_
|
| Weapons doesn't pay as well as making people click ads. The
| people working on this stuff are usually doing so because
| they believe it's the right thing.
| autoexecbat wrote:
| > less interested in being part of the MIC than they used to
| be
|
| It's just TC being too low
|
| Plenty of us are happy, even pleased, to make weapons.
| petertodd wrote:
| I'd hope some of these employees are looking at what is
| happening to Ukraine and reconsidering their positions.
| Without weapons of your own, you're beholden to unfriendly
| nations with their own weapons.
|
| Certainly I get the sense that a lot of Ukrainians have
| reconsidered _their_ own views. There 's people I know who I
| doubt would have ever involved themselves in weapons
| development, who have gotten into it and related things.
| throwaway2562 wrote:
| Agreed, this has nothing to do with passenger flight, and the
| pretense is gross.
|
| Thin vernier -> thin veneer btw
| credit_guy wrote:
| No. A lot of hypersonic stuff is partly classified. So the
| journalists are left with the definition: hypersonic speed is
| Mach 5 and higher. Mach 5 is where the heat produced in the
| boundary layer (by compression, mainly) is high enough that
| chemical reactions take place and you need to account for them
| in your computational fluid dynamics.
|
| As a rule of thumb, when you hear boost-glide vehicle, the
| speed is close to Mach 20. If it's air breathing (ramjet or
| scramjet) the speed is slightly higher than Mach 5, but
| probably less than Mach 10.
| euroderf wrote:
| I appreciate the sentiment, but it sounds a bit like the case
| of I.T. vis-a-vis the NSA. As James Bamford said, one
| expects+assumes that the NSA is way ahead of the state of the
| civilian art. They have the budget.
|
| Likewise this case. As an OTL civvie I'd expect that this tech
| under discussion lags whatever .mil is up to. Out to launch!
| axus wrote:
| Maybe they can catch up and end up with a more cost-effective
| rocket, like SpaceX. But probably not.
| jandrewrogers wrote:
| You could make the same argument for a lot of software tech
| startups.
|
| If you develop state-of-the-art data infrastructure software,
| novel data processing capabilities, or some other advanced
| software tech, it is routine to have an org under the US DoD as
| one of the earliest pilot customers. It is an open secret but
| many startups pretend like this isn't a standard part of that
| kind of business. The US DoD is a sophisticated early adopter
| of a lot of tech at a stage before most commercial enterprises
| are willing to engage.
|
| The average person on the street may be a bit naive about this
| but the majority of deep tech startups are de facto "dual use"
| and none of this should be a surprise to someone that works in
| deep tech.
| JumpCrisscross wrote:
| > _mach 5 for a reason, which is that the material science
| hasnt caught up yet_
|
| The X-15 did Mach 6 in the 60s. What materials and components
| are you referring to as cliffing us at Mach 5? Isn't the
| simpler explanation that hypersonic flight is defined at Mach
| 5?
| jtriangle wrote:
| The X-15's had to be repainted after every flight, because
| the ablative coating was designed to wear off at speed.
| That's a huge expense, in both time and money. Worth it for a
| research craft, not worth it for any practical use.
|
| In terms of materials, most of the newmake ultra fast
| aircraft are using inconel, which is more viable than it was
| back in the day. Some are using ceramic coatings of various
| sorts in hopes that they'll be able to develop something
| strong enough to be reused.
|
| And that's not to say that they won't be able to come up with
| something, just that nobody has done it yet, or, has done it
| and has talked about it.
| topspin wrote:
| Weird that the term "drone" is used for what is plainly a
| missile.
| readyplayernull wrote:
| Every vehicle is a drone as every algorithm is AI now.
| Marketing keeps the world rolling.
| morkalork wrote:
| Cruise missiles that have wings and follow flight plans
| rather than ballistic trajectories are pretty much just
| drones and always have been.
| topspin wrote:
| Another comment points out the inevitability of this
| technology appearing in weapons long before any sort of
| passenger aircraft. So the likely marketing reason is a bit
| of gaslighting to avoid "issues" with some investors.
| nonrandomstring wrote:
| > every algorithm is AI now
|
| Dammit, I'm still working with computer "programs", you crazy
| kids!
| carabiner wrote:
| No warhead and it's meant to be reusable. Very different
| engineering for an actual missile weapon that is intended to
| fly once.
| hawski wrote:
| In certain scenarios it makes sense and is very effective to
| turn off GC in Java, because then most allocations would be
| just a bump. It is much easier to turn it off than have a
| system without it and turn it on.
| buildsjets wrote:
| No, it's weird that people think that only those dumb looking
| quadrotor helicopters are "drones", when "drone" was originally
| a term used for an unmanned missile or aircraft decoy. This
| usage dates back to 1936 or earlier.
| 1letterunixname wrote:
| That R/C planes, helicopters, and toys need bureaucratic
| government licensure is only explainable as outgrowth of
| "helicopter" (pun intended), fear-based parenting and the
| elimination of everything fun that might have the slightest
| potential risk and the acquiescence to intrusive control.
| snakeyjake wrote:
| Some of the first non-apian drones to ever fly were "missiles".
|
| You're going to have to invent time travel, go back over a
| century, and murder all of the people who started calling
| drones "drones" if you want to win this battle.
| 1letterunixname wrote:
| A crushed bit of paper could be a "missile."
|
| The mass media put its thumb on the scale, lambasting
| phenomena by reforging certain words to create a culture of
| fear and taboo using such example words as "hacker",
| "terrorist", and "drone".
|
| And while a Unabomber approach to language use is unlikely to
| influence anyone, it's important to know the history of
| multiple meaning of words because those are additional
| meanings because a single word means different things to
| different people based on situational factors. To suggest one
| meaning is more "right" than another is to champion some
| people's experiences and invalid others'.
| mc32 wrote:
| Speaking of detonations, NASA is till interested in nuclear
| propulsion to reach Mars. This is reminiscent of projects Nerva
| and Orion/:
| https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
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